Molecules that include arene groups associate through supramolecular interactions to produce aggregates by arene stacking (also referred to as pi-pi stacking). One example of an arene stacking configuration includes stacking whereby two parallel arenes associate off-centered in a “slipped” stacking configuration. Another example of an arene stacking configuration includes perpendicular arenes that associate in an “edge-on” stacking configuration. Yet another example of an arene stacking configuration is a configuration in which perfluoroarenes with electron-rich arenes are oriented in a parallel-displaced or “face-to-face” configuration, representing the most stable configuration.
The interaction between single arene molecules is generally a weak supramolecular interaction (e.g., having ΔG of about −1 to −2 kcal per mole). However, these weak supramolecular interactions are generally considered additive. Accordingly, while the interaction is weak between small molecules, the interaction can be orders of magnitude stronger when these functionalities are present in repeat units of a polymer.